The double cartridge cases to be operated by the dispensing appliance serve in known manner for processing so-called two-component substances, both components of which are stored in separate cylindrical containers and, upon the plungers being acted upon, are delivered through the cartridge opening. In this arrangement, the components are customarily combined and mixed thoroughly in a static mixer adjoining the cartridge outlet. When operating double cartridges by means of dispensing appliances of the above-mentioned kind having a (most often pneumatically driven) cylinder/piston unit, the particular problem is encountered that the piston during the pressurization tends to canting and tilting because the reaction forces of the two adjacent rams acting upon the piston can be significantly different. Such differences are primarily caused by different viscosities or discharge resistances of the two components to be expelled and/or by different cross-sections of the two cartridge cases and plungers corresponding to a mixing ratio for the particular two-component system different from 1. Such unavoidable tilting momentum at the appliance piston leads, of course, easily to jamming or defective sealing of the piston or to other functional failures.
Removing these difficulties did not seem simple until today: either the two rams and especially their connection to the piston must be resistant to bending, or an excessively long piston guidance at the cylinder in connection with a cylinder wall able to resist local bulging had to be provided. Both measures, however would, as far as they would be effective at all, cause the dispensing appliance to weigh considerably more and, hence, would make the manually operated, most commonly pistol-shaped appliance difficult to handle.
It is the task of the invention of building a dispensing appliance of the mentioned kind so that widely different reaction forces by the two rams during the piston advance do not affect function and handling of the appliance in a negative manner.